1. Field of the Invention
The present invention relates to a boom assembly swingably supported to a receiving bracket attached to a front of a swivel table of a swiveling utility vehicle such as a backhoe.
2. Description of the Related Art
In a backhoe, for instance, a swivel table is supported to a vehicle body having a crawler traveling unit, with the table being swivelable about a vertical shaft and a boom assembly is attached to the front of this swivel table.
In the boom assembly, a swing bracket is supported via a receiving bracket to the front of the swivel table, with the bracket being pivotable about a vertical axis. To this swing bracket, there are connected a base end of a boom formed as a hollow structure having a bent intermediate portion and also an end of a boom cylinder for lifting the boom. At the leading end of the boom there is pivotally supported, via a pivot shaft, a base end of an arm formed as a hollow structure. A pair of right and left connecting brackets are provided adjacent the pivot shaft for the arm. An arm cylinder for moving up and down the arm is connected between the connecting brackets and the boom. The arm pivotally supports at the leading end thereof an implement such as a bucket. An implement cylinder for pivoting the implement is connected between the implement and the connecting brackets.
Further, in the boom assembly of the above type, a hydraulic pipe for a bucket cylinder, an external or auxiliary hydraulic implement or the like is often provided on the outer side faces of the boom and the arm. However, a different construction is known from e.g. Japanese Patent Application “Kokai” No.: Hei. 11-13083, in which the hydraulic oil pipes are inserted within the boom and the arm connecting brackets. More particularly, in this boom assembly, the hydraulic oil pipe for external implement is extended to the vicinity of the arm and a hose joint acting as a service port is attached to the top face (back face) of the arm, so as to allow the external hydraulic implement to be used at a position far from the swivel table. However, since the hose joint is attached to the top face of the arm where the bucket cylinder is provided, there tends to occur interference between the hydraulic oil pipe connected to the hose joint and the further hydraulic oil pipe connected to the bucket cylinder, so that with activation of the bucket cylinder, the two oil pipes can come into sliding contact with each other to be damaged thereby. Also, because of the presence of the bucket cylinder, a connecting operation of the hose to the hose joint is difficult.